Transmission system for radiant energy



July 26 1927. 1,637,310

Y J. H. HAMMOND, JR

TRANSMISSION SYSTEM FOR RADIANT ENERGY Original Filed Sept. 28, 1917 Patented July 26, 192?.

JOHN HAYS shaman, an, or ere-amass; MAssAcnos'nrTs.

TRiAiN SMISS IUN SYSTEM FOR RAIDLAN'It ENERGY.

Application filcd September 28, 1917 Serial No. 193,827. Renewed August 1 1924.

modify, through the action of suitable means, preferably, a secondary high- "acuum, onized gas or thermionic valve, or other suitable valve, and at a. frequency above good audibility, the high frequency oscillations produced by the primary valve, to providean improved receiving system for radiant energy, to providea system for secretly transnintting signals. to provide, an

improved selective system for the transmission of radiant energy and to provide other improvements as will hereinafter appear.

1n the accompanying drawing 1 N Fig. 1 is a diagrammatic sideelevation of a transmission sys em constructed in accordance with this invention; Fig. 2 is a diagrammatic side elevation of a receiving 4- tcin constructed in accordance with this iiivention; and Fig- 1. 3 and a are graphs explanatory of the operation of this improved system. i v

Referring to the drawing, and particularly to Fig. 1. which shows one form of transmission system constructed in accordance with this invention, an antenna 1 is grounded at 2 and includes an inductance coil 3 provided with an adjustable tap l. The antenna 1 also includes a direct-current generatorh, or other source of high potential direct-current, arranged to give a suitable potential, for instance, from 500 to 1,000 Volts. A variable condenser 6 is shunted around the generator 5 to permit high frequency oscillations in the antenna 1 to pass around said generator 5. H

For setting up electrical oscillations in the antenna circuit 1, 2 any suitable valve, for instance, a high-vacuum, ionized gas or thermionic valve 15, may be provided; Theillustrat ed valve is of well known construction and comprises a glass bulb 1 5, the interior of which is highly evacuated aiid containsa filament electrode 16, a grid electrode 1.7 and a plate electrode 18. The filament elect-rode is arranged to be heated by a battery l9oper-t ated through a rheostatflO. Oneend of the filament lG is connected by a conductor 21 to the hereinbefore described adjustabletap l. The grid 17 is connected by conductor 21 to one side of a variable condenser 22, the other side of which is connectedbya con; doctor 23 to the lower end of the inductance coil An inductance coil 25. is shunted around the variable condenser 22 to'perniit, directcurrent to pass around the condenser 22 and toform a closed, oscillatory circuit 26 including the variable condenser22 i The plate electrode 18 is connected by a conductor 27 to the antenna circuit 1. k s The elements of the transmission system thus far described may be operated to produce strong, continuous oscillations in the antenna; circuit 1, 3, 2. The frequency of these oscillations Will depend mainly on the. dimensions of the coil 3 and the constants of the antenna and ground 1 2 aud o ily slightly on other local conditions such, for ex; ample, as the temperature of the filament l6 and the voltage of the generator 5.

For i npressing upon the high frequency oscillations set up in the antenna circuit 1 2, as described, periodic variations of an plitude, an auxiliary coil 30 is arranged so as to inductively upon the hereinbefore described inductance coil 25 auxiliary coilSQ thus forming the pri- -mary of a transformer 31 Which iiicludes inductance coil Any suitable means may be provided for S gttlIlg up electrical oscillations of a su table frequency in the auxiliary @011 30. In the form of the invert tion shown, a secondary, high-vacuum, i011- ized gas or thermionic valve 35 is one of the elements used for this purpose, This secondary valve 35. is similarin construction tothej primaryv ang 1 5 hereinbefoie described, and includes a glass bulb' 36 the interior of which is highly evacuated and contains a filament electrode 37, a grid electrode 38 and a plate electrode 39. The filamentelectrode 37 is arranged to be heated by a battery 40 operated through a rheostat 41. The plate electrode 39 is connected by a conductorl l l to one pole of a direct Current, electric generator 45 m. other source of a high potential' direct-current, the other pole of which is connected by a conductor: 46 to one endofthe aux iliary coil 30. The other ,endlof the auxiliary coil 30 is connected by a condoctor 47 to the grid electrode 38. A vaand circuits is such that when the generator 45 is in operation, strong, continuous, electrical oscillations will be produced in the auxiliary coil 30 having a frequency determined mainly by the inductance of the coil 30 and the capacity of the variable condenser 55, and these oscillations will be impressed upon the circuit of the primary valve 15 through the action of the transformer 31 and will cause corresponding periodical variations in the amplitude of the oscillations set up by the primary valve in the antenna circuit 1, 3, 2. A key 60 or other suitable signaling device may be arranged in any suitable position in the system, as for instance in the circuit 58 of the secondary valve 35.

In the operation of the entire transmission system shown in Fig 1, the parts are,

preferably so proportioned and arranged that under the control of the primary valve 15 electrical oscillations having a frequency of, for instance, one million cycles per sec- 0nd, will be set up in the antenna circuit 1, 3,2, and that oscillations of, for'instance, thirty thousand cycles per second will be set up under the control of the secondary valve 35 in the closed, oscillatory circuit 56, which includes the auxiliary coil 30. As a result ofthese oscillations in theclosed, oscillatory circuit 56, theclosed, oscillatory circuit 26 is resonated approximately at the rate of thirty thousand oscillations per second.

The function of the secondary valve 35 is to impress through the transformer or coupling 31 a periodical Jpotential fluctua tion on the grid 17 of the primary valve 15, for instance, in the case noted a potential fluctuation of thirty thousand cycles per second. With the frequencies assumed above, this causes the amplitude of the oscillations of one million "cycles per second set up in the antennacircuit 1, 3, 2, to fluctuate periodically at a frequency of'thirty thousand cycles per second. The antenna circuit 1, 3, 2 will thus be caused to emit corresponding electro-radiant oscillations, having, for instance, an oscillation or wave frequency of one millioncycles per second and a periodical amplitude variation frequency of thirty thousand cycles per second.

In F igs."3 and 4, the passage of time is 103. The coil 102 forms the primary of a plotted horizontally and. the amplitude of the oscillations is plotted vertically, while the horizontal line indicates zero potential. In Fig. 3 the electrical oscillations set up in and consequently radiated from the antenna circuit 1, 3, 2 under the control of the primary valve 15, unintluenced by the secondary valve 35, are indicated diagrammatically by the full curved line 80, the time 81 between successive waves being, for instance, one one-millionth of a second. In Fig. 4 the full curved line 85 indicates the form of oscillations set up in and consequent ly radiated from the antenna circuit 1, 3, 2 while under the influence of both the primary valve 15 and the secondary valve 35, the time 81 between successive waves being, for instance, one one-millionth of a second, and the time 87 between periodic amplitude variations of the waves being, for instance, one thirty-thousandth of a second.

For receiving the complex, electro-radiant oscillations emitted by the transmission system shown in Fig. 1, a receiving system of the form shown in Fig. 2 may be used. This system comprises an open aerial circuit including an antenna 101 and an inductance coil 102 which is grounded at step-up transformer 105 including a secondary coil 106 which is connected in a closed, oscillatory circuit 107. The circuit 107 con tains a variable condenser 108 and is arranged in a well known manner to control through a condenser 109 a primary, highvacuum, gaseous detector 110, or any other suitable detector.

The primary detector 110 shown is similar in construction to the primary valve 15 hereinbefore described and includes a highly vacuumized glass bulb 110, a filament 111, a grid 112 and a plate 113. The filament 111 is arranged to be heated by a battery 114. The primary detector 110 is arranged to control a circuit including a battery 115 and an inductance coil 116, which is arranged in an oscillatory circuit 117 including a variable condenser 118. The coil 116 forms the primary of a transformer 120 which includes a secondary coil 121 connected in a secondary, closed, oscillatory circuit 125. The circuit 125 contains a variable condenser 126 and is arranged to control, through an inductive coil 127 and a condenser 128, a suitable secondary detector 130 which, as shown, is constructed as hereinbefore described.

The secondary detector 130 is arranged to control a circuit including a battery 136, receiving telephones 137, or other receiving device, and a periodic interrupter 138. The interrupter 138 may be of any well known or suitable construction, and is rotated or operated to interrupt the circuit 130 135, 136, 137 at a uniform predetermined rate Within the range of audibility, for instance, 1,000 times per second, to render the unidirectional pulsations in the controlled circuit 135, 136 audible in the'telephones 137, as will hereinafter appear. A-condenser 140 maybe arranged in shunt around the tele phones 137 orother receiving device to provide a closed, oscillatorycircuit 141 which is preferably tuned 'to the frequency of the interru 'ter 1238-01 of the beats which may be pro need as will hereinafter appear in the*circuitcontrolling "the secondary detector 130-to build up selectively currents having the frequency 'ofthe interruptions -produced in the circuit '135, 136 by the interrupter 13801- having the "frequency of the beats.

For impressing upon the circuit controlling the secondary detector 130, loc-ally:pro duced oscillations having a suitable frequency relatively to that of the oscillations produced in thecircuit'througlrthe action of theprimary detector 110, an auxiliary induction coil "150is positioned in inductive relation with the hereinbefore described coil 127and is arranged in a closed circuit 151 energized by anyelectrioal alternator 152 or other suitable source of electric oscilla tions.

In'the o eration ofthe receiving system shown in l ig. 2, when used in connection with the hereinbefore described transmission system shown in F ig. 1,' the open, aerial circuit is preferably tuned to respond to the high frequency o'tthe transmitting system, i'or instance, one millionoscillations per second, and the closed oscillatory circuit 107 is accordingly tuned to the same frequency. The primary, closed circuit 117, which iscontrolled'by the primary detector 110, is tunedto the secondary *i'requency of thetransmission system, for instance, thirty thousand oscillations per second, and the secondary, closed circuit 125 controlling the secondary detector 130'is accordingly tuned to the last-named frequency. The circuit which includes the a'uXili-arycoil 150 and the alternator 152 may be arranged to produce, for instance, thirty one thousand oscillations per second in the auxiliary coil 150.

Now when the electro-radiant oscillations or Waves having a predetermined Wave frequency of, for instance, one million cycles per second, and a predetermined amplitude variation frequency of, for instance, thirty thousand cycles per second, as shown diagrammatically in Fig. 4, are received by the open, aerial circuit 100, corresponding oscillations are set up in the aerial circuit and in the closed, oscillatory circuit 107 controlled thereby and itself controlling the primary detector 110. This causes corresponding variations in the current normally flowing through the circuit 115-416 controlledbythe primary detector and prod'uces unidirectional pulsations in the closed circuit 117 of the same frequency as the secondary frequency of the received waves, for instance, thirty thousand cycles per second. The oscillations in the closed circuit 117 produce corresponding oscillations in the secondary, closed circuit 125 which act through the sccondarydetector 130 to correspondingly vary the current normally flowing through the controlled circuit 135, 186, 137, 138 to produce unidirectional impulses of a i requency of thirty thousand cycles per second. These impulses being of a frequency above audibility cannot be heard in the telephones 137 except as the result of the operation of the interrupter 138 or of the oscillatory circuit 151.

hen the interrupter 138 is stationary and in a closed position, completing the circuit through the detector 180 and telephones 137, and the alternator 152 is in operation to produce oscillations of a lreqi'iency of, for instance, thirty-one thousand 63 016311381 second in the auxiliary coil 150, these oscillations act inductively upon the coil 127-to produce ci'lrresponding oscillations in the circuit containing thecoil 127 and controlling the secondary detector 130. The oscillations con'ibine with thirty thousand cycles per second in the circuit including coil 127 and: producetherein beats having atrequency of 1,000 cycles per second. These beats act through the secondary detector l30to cause corresponding ui'iidirectional impulses of one thousand cycles per second in the circuit 135, 130, i137 controlled by the secondary detector 130, and these impulses are audible in the 'tele phones 137.

If, instead of the telephones 137, some other receiving device which does not 'lunc-' tion toproduce audible sounds, such,-for instance, as a relay, should be employed, it would not be necessary to use the interrupter 138 or the oscillatory circuit 151. The closed, oscillatory circuit 151, however, might be utilized for the purpose of producing amplificatiol'i of the impulses in the circuit controlled by the secondary detector 130 and a consequent increase in effectiveness in controlling a relay or other receiving or signaling instrument.

VVh-at I claim is:

1. A system of radio transmission, comprising an aerial circuit including a source of current, means including athermionic valve cooperating With said source to produce electrical oscillations in said circuit, and means including a thermionic valve arranged to impress periodic amplitude variations upon said oscillations.

2. A system of radio transmission, comprising an aerial circuit including a source of high potential direct current and an in the oscillations of ductance, a condenser shunted around said source, means including a thermionic valve cooperating with said source and said induc tance for producing electric oscillations in said circuit, said valve including ionizing means variably connected to said inductance, and means inductively connected to .said

first-mentioned means for impressing periodic amplitude variations upon said oscillations.

3. In a system for selective radio transmission, a transmitting system comprising means including a thermionic valve for producing high frequency electric oscillations, means for impressing upon said oscillations periodic amplitude variations of a frequency above goodaudibility, and a receiving system including cooperating receiving circuits tuned respectively to the frequencies of said oscillations and said variations and provided with an interrupter acting at an audible frequency.

at. In a system forselective radio transmission, a transmitter comprising means'for producing high frequency oscillations, including a thermionic valve having plate and grid circuits connected in inductive relation, an oscillatory circuit connected in said grid circuit and means for impressing thereon oscillations of a frequency above good audibility and thereby causing said valve to produce oscillations modulated in accordance with said second mentioned oscillations, said last mentioned means including a thermionic valve and a closed oscillatory circuit connected therewith and inductively coupled with the first mentioned oscillatory circuit.

5. In a system for selective radio transmission, a transmitter comprising means for producing high frequency oscillations, including a thermionic valve having plate and grid circuits connected in inductive relation, an oscillatory circuit connected in said grid circuit and means for impressing thereon oscillations of a frequency above good audibilityand thereby causing said valve to produce oscillations modulated in accordance with said second mentionedoscillations, said last mentioned means including a thermionic valve and a closed oscillatory circuit connected therewith and inductively coupled with the first mentioned oscillatory circuit, and signalling means incorporated in the external circuit of said last mentioned valve for selectively causing generation of said lower frequency oscillations.

(3. A system of selective radio transmission comprising a thermionic oscillator for producing high frequency electrical oscillations, said thermionic oscillator having included in its grid circuit a closed oscillatory circuit adapted to control the amount of curcircuit adapted to control the amount of current flowing in said grid circuit, a second thermionic oscillator adapted to oscillate at a lower but supersonic frequency and inductively coupled to said closed oscillatory circuit to control at said lower frequency the amount of current flowing in said grid circuit and thereby the amplitude of the high frequency oscillations produced by said first mentioned thermionic oscillator, and signalling means incorporated in said last mentioned oscillator circuit for selectively causing generation of said low frequency oscillations and thereby the modulation of said high frequency. y

Signed this 25th day of Sept, 1917.

JOHN HAYS 'HAMMOND, J n. 

